Modified milk and process for making the same



Patented Uct. IA, TARA.

GEORGE GRDIDROD, F OCONO'MOWOC, WISCONSIN, ASSIGNOR 'IO CAR/NATION MILKPRODUCTS COMPANY, OF OCONOMOWOC, WISCONSIN, A CORPORATION OF DELA- WARE.

No Drawing.

To all whom it may concern:

Be it known that I, GEORGE Glimnnon, citizen of the United States, andresident of Oconomowoc, county of Waukesha,

State of Wisconsin, have invented certain new and useful Modified Milksand Processes for Making the Same, of which the following is aspecification.

This invention relates to modified milks or what is known as artificialhuman or mothers milk and processes for making the same.

Heretofore, various forms of modified milk have been proposed, but noneof these 1 have successfully accomplished the object for which they wereintended. Among the modified milk heretofore proposed, some weremodified to some extentin .fat and sugar content only, but were notmodified in ash content. uch products would not keep for a sufficientlength of time to permit successful marketing, and in general did notmeet the requirements. Furthermore, such milks were subject tocrystallization of lactose, fat separation, spoiling by spore-formingbacteria on account of complete sterilization, and were Subject also tospontaneous decomposition of the -protein, due to chemical changes notinitiated by bacteria. Such modified milks, as heretofore proposed, werealso subject to separation of the colloid aggregate from the milk serum.Other than these unsuc-- cessful efforts, no one'has attempted. toproduce an equivalent of human milk from cows milk in sucha combinationas to permit condensation, canning and sterilizing, in a manner to keepindefinitely.

As stated, condensed modified or human-- ized milk, has heretofore beenfound to undergo slow separation and decomposition of the protein evenwhen sterilized. Numerous investigations and tests made by me caused meto conclude that one reason for this was the catalytic action of theinorganic salts of the milk, which are in increased concentration in acondensed product. When additional crude lactose or whey was added, aswas done in some of the products heretofore proposed, the inorganicsalts of the lactose further increased the concentration of such saltsand accelerated the decomposition of proteins. To prove this, I prepareda quantity of inorganic salts of milk and added them to con- MODIFIEDMILK AND PROCESS FOR MAKING THE SAME.

Application filed January 17, 1920. Serial No. 352,184

densed modified inilk in varying proportions, and I found that the rateof spon taneous decomposition varies directly as the proportion ofinorganic salts present. Im"

purities in the lactose tend further to cause they entangled would riseto the upper part of the container and allow the serum to separate tothe bottom. This separation of the colloid aggregate, that is, thecolloidal constituents and the fatentangled therewith, has beenheretofore attributed to lack of proper combination of the constituents.The inability to separate milk into its constituents, and recombine themin other proportions and make a stable compound, has heretofore been oneof the chief difficulties in the way of making a permanent or stablehumanized milk which could-be condensed.

Evaporated cows milk is well known to be a stable product, keeping incans without' separation of [fat or serum, for years. But while thefirst attempts at condensin canning and sterilizing humanized mif werebegun at about the same time that the process of making evaporatedsterilized cows milk was discovered, there is as yet no evaporatedsterilized humanized milk on the market. Condensed humanized milk hasnever beenv found to keep uniformly but separates into a layer of serumand a layer of fat-portein.

This tendency of condensed humanized milk to separate was thought byearly in ventors in this art to be due to lack of homogenizing, but withthe invention and use of homogenizing machines, the separation was foundto continue as before, and homogenizing, although a well known processfor many years, has not resulted in the production of a. condensedhumanized milk as a stable marketable commercial article...

I have fully investigated the cause of this marked difierenoe betweenthe stability of rod evaporated cows milk and evaporated humanized milkand have found the cause and remedy for lack of stability in evaporatedhumanized milk tobe as follows:

Upon subjecting stable, evaporated cows p milk to a process ofultrafiltration, I sueceeded in separating it directly into two parts,(a) a clear serum containing only 0.25% protein, all the lactose andinorganic salts, and (b), the colloids and the fat.

Since an ultrafilter of any type is a filter capable of separatingc'rystalloids from colloids, this method indicates that in the processof condensing and sterilizing the proteins of milk are thrown completelyinto the colloidal state, with the exception of a residual 0.25%, which,according to my results, appears to be a constant non-colloidalconstituent.

1 determined the specific avity of the clear serum from evaporate milksknown to be stable, and found in all cases a serum I specific gravityequal to or slightly less than the specific gravity of the colloidaggregate. Since it has long been known in the evaporated milk industrythat the most stable product is obtained at a concentration of 2 to 1, Iconcluded that this particular concentration found by experience, 15 thepoint at which the serum'specific gravity.

equals that of the colloid aggregate, in cows milk. Since the specificgravity of the colloid aggregate is constant regardless of concentrationand that of the serum increases with concentration there is a point, and

only one poin'tof concentration for any given composition of milk atwhich the spe- ,cific gravity of the serum equals the specific gravityof the colloid aggregate. At this point, an inseparable stable product1s obtained.

I obtain samples of condensed sterilized humanized milk which hadseparated after being placed on the market, and subjected them to thesame process of ultrafiltration and found thatin them, the serum wasdecidedly heavier than the colloid aggregate,

thus accounting for their lack of stability.

I next made condensed humanized milk by the process herein described,determining the point of concentration, producing stability by themethod hereinafter described, and found, the product to be stableagainst separation for ariod of one year, and apparentlyindefimtely'stable.

f These investigations have shown that (1) the density of .a humanizedmilk must" bev in accord with its composition, (2) the point ofconcentration is difierent from that of evaporated cows milk, (3) thepoint of concentration must be determined and is an essential to themanufacture bf a stable roduct, 4) an adaptation of the princip e ofultra ltration is a successful method for the control of manufacture.

desired quantity of The method and apparatus employed in applying theprinciples of ultrafiltration for the purpose above referred to aredistinct from the method and apparatus heretofore used, although theprinciple remains the same, ultrafiltration being understood to meanspecifically the separation of crystalloids from colloids by filtration.Ultrafiltration has heretofore been carried out as follows A pure heavycellulose filter paper has.

been caused to gelatinize by meansof sulphuric acid of approximately 66%at a temperature of approximately 15 Centigrade, thus producing amyloid.The filter paper I was by this means rendered semi-permeable and capableof separating crystalloids from colloids by direct filtration ifsufiicient pressure were placed on the liquid to be filtered. On accountof the clogging of the pores of quantities of the liquid could befiltered, and

.then only liquids of very low viscosity, such colloids of differentsizes from crystalloids,

I concluded that infusorial earth could be utilized in place of theamyloid membrane for the purpose of ultrafiltration. I, accordingly,mixed with the milk to be filtered, usinga quantity of. 200 to 5OQ ccs.,sufiicient 'such a membrane, however, only minute,

infusorial earth to form a thick paste and then subjected this paste toaheavy hydrostatic pressure in a specially. constructed funnel, using arubber membrane to se arate the paste from the water. By t is means I'was able to separate a clear serum from the milk instantl and to filterany e milk. The infusorial earth onthe application of pressure settlesinto a compact mass having a porosity such that colloid particles cannotpass through it, and at the same timeofiering a very large area in whichto retain the gelatinous colloids. Instead of a thin amyloid membrane,the filter prepared in this way may be from two centimeters to fivecentimeters thick. Frequently the first few cubic centimeters passin'gfrom the filter willcontain some colloids, but as soon as the infusorialearth forms a layer a few millimeters in'thickness, the colloids ceaseto pass and." an apparently clear serum is removed from the milk.process inretiree stead of requiring several hours, as in rocesses ofultrafiltration heretofore use requires only a few minutes and so isadaptable to the manufacture of the present product.

After the separation of the non-colloid serum from a sample of the milk,its specific gravity is accurately determined, and from the specificgravity'of the serum and the specific gravity of the original milk, thespecific gravity of the colloid aggregate may be calcu ated it beingunnecessary to separately determine the specific gravity of the colloidaggregate.

Having determined the specific gravity of the colloid aggregate of agiven composition of milk, the extent of concentration required toproduce stability may be calculated. Thus, if the specific gravity ofthe colloid aggregate is found to be, for example 1.07 and the specificgravity of the serum from the uncondensed milk is found to be 1.04, theextent of concentration required is the ratio of 7 to 4. When the entiremilk is condensed in this ratio the specific gravity of the serum willthen be 1.07. or identical with that of the colloid aggregate andconsequentl the colloid aggregate cannot separate from the serum. 11prac: tice, condensation is carried slightly past the calculated point,the condensate then analyzed and specific gravit Y determined afterwhich a'small amount 0 water is added to bring the specific gravity ofthe milk to the exact point required.

For any particular proportion of fat, protein and lactose in modifiedmilk there must be a certain point of concentration at which the densityof the serum equals the density of fat protein entanglement, and

this is the point to which the particular composition in question mustbe condensed in order to be in stable suspension. The serum may have aslightly less specific gravity than a fat protein entanglement withoutdanger of separation. Tn ractical manufacture a certain margin 0variation must always be allowed in order to make the process practical,and certain variation in conlmsation is permissible in this product.Such variation as occurs in the manufacture of a condensed modified milkmust be so regulated that the specific gravity of the serum does notexceed the specific gravity of the colloidal aggregate. But the specificgravit of the colloidal aggregate may slight y exceed the specificgravity of the serum without resulting in serious separation.

The com osition of. human milk is not fixed and efinite, but variesconsiderably, and the composition instead of being a fixed percentageofthe several constituents, is in fact a range of percentage or proportionfor three princi al constituents, namely, fat, protein and actose, isvaried, the point of condensation must also be varied. It is desirableto manufacture a product which is condensed either in the ratio of twotoone, or in'some other even ratio, and it is therefore advisable tomodify the proportions of the constituents sli htly in order to make thepoint of stability occur at some even ratio of concentration. A range ofpermis sible variation from the point of theoretical stability ispractically the same as that allowable in evaporated milk. Roughly thefat may vary a few tenths of a per cent one way or the other withoutresulting in separation, and the same is true of the other constituents.

T have found that the modified milk having a composition of 7% butterfat, 5% protein and 12% lactose is stable. This is substantially a twoto one concentration of human milk having an original composition If thepercentage of fat is increased above 7% by any appreciable amount; thepercentage of protein must also be increased. If the percenta e oflactose is increased the percene 0 protein must be increased. If thepercentage of lactose is decreased the percentage of fat may beincreased, or the rotein may be decreased. It might, thereore, be saidthat in general, a modified human milk which is stable must havecompositions approximately within the followmg ranges: fat 7% to 9%,protein 4.5% to 5.6%, lactose 11% to 14%. If the composition is variedmaterially-outside an of these ranges the milk is no longer 0 averagehuman milk composition. It is obvious that it would be practicable tolower the lactose, increase the protein, and increase the fat,approaching the composition of cows milk and at the same time maintain astable composition, but percentages out of the ranges specified vary toomuch from those of human milk to make the product suitable for infant of3.5% fat, 2.5% protein and 6%lactose.

feeding. Points of stability at suitable con-' centration can be foundwithin the ranges specified, thus keeping the composition with in therange of average human milk and at the same time so balancing thecontituents as to make the product stable.

,Furthermore, attempts at sterilization of condensed humanized ,milkhave'resulted in variable success, some batches withstandingsterilization, while others of apparently the same compositioncoagulated in the process. In general, humanized milk has been founddifficult, if not impossible to sterilize if condensed, since theprotein'willi'coagulate before a sterilizing temperature can be reached,it beingnecessary to sterilize any canned milk product ata temperaturenot less than 233 F. for thirt minutes or the equivalent, which is theeath point of a spore former'heretofore called Paraplectum foetidium(Bjrinck), or Plectridium foetidium (Hunziker), but now known to be avariety B. butyricus.

A higher temperature, or a longer time of sterilization than 233 F. for30 minutes has been found necessary in the eastern and central parts ofthe United States. On the- Pacific coast in my experience 233 F. for 30minutes was sufficient to kill the sporeforming bacteria but in centraland eastern United States a more resistant st'rainof the- B. butyricushas been found, and also more resistant bacteria of other species. Inthese districts it has therefore been necessary to sterilize milk fornot less than 16 minutes at 242, or 40 minutes at 233. The formertreatment using a higher temperature has been found more safe andcertain of sterilization than the lower temperature.

Prior inventors in this art, for example,

Trudel, Patent No. 1,039,849, have thought that variable coagulabilityis due to acidity and have fixed limitations of acidity permissible. ButI have found acidity to be a minor factor in determining coagulabilityof humanized milk, the principal cause of the variablecoagulation'beingdue to the presence of abnormal proteins in theoriginal principles In practice, the test is carried out underconditions necessary to the selection of a.

milk capable of withstanding sterilizing after its evaporation at atemperature of .1 233 F. for thirty minutes, or the equivalent of thisamount of time and heat in any other combination of time andtemperature.

The coagulation of the proteins of milk through the agency of heat-isknown to have a relationship to the inorganic salts of the milk, and thecoagulation is known to be'greatly facilitated by increases in ceraininorganic salts. .I have, accordingly, fully investigated therelationship of the inorganic salts of the milk and the coagulability ofthe proteins and have found that the calcium citrate is chieflyresponsible for the coagulation of proteins which are normal. I havealso found that with a particular sample of milk having a fixedinorganic salt content, the coagulability follows the laws of catalysis,and'the inorganic salts, especially, the calcium citrate, appear to be1,511 see the catalytic agents causing the coa lation. Accordingly, thecoagulation o the protein in a sample of milk having a. given content ofinorganic salt varies as the time to which the sample lSwBX to a giventemperature. I have also found that if the inorganic salt content isvaried, as for instance, by diluting the milk with pure water, or byconcentrating the milk by evaporation in a vacuum, the rate ofcoagulability increases as the salt content increases, or decreases asthe salt content decreases, other conditions being constant. Therefore,the coagulability of milk if condensed may be predicted from itscoagulability in the uncondensed state. If it is required that thecondensed milk be capable of withstanding sterilization at 233 F. forthirty minutes and the ooncentrationofthe inorganic salts is to be inthe ratio of 2 to 1, the uncondensed milk Wlll undergo the. samecoagulation if heated to 233 F. for sixty minutes, or the uncondensedsample could be subjected to a higher temperature for a shorter lengthof time, such that its coagulation in the uncondensed state will be thesame as that which it would undergo in the condensed state. The factthat the tendency to coagulate in a given sample of milk follows thelaws which permit of the prediction as to what the original milk will doafter being condensed, permits of the selection or grading of milk andthe utilization of only such milk as will withstand sterilization at therequired temperature. Before accepting milk for use in the manufactureof humanized milk a sample from each can or each unit of the originalmilk me. be subjected to the coagulation test an its eoagulabilitydetermined and the coaafulable milk eliminated before the milk is ded tothe mixture. Also, the batch or mixture of milk utilized may be kept ata uniform degree of coagulability.

The test for predicting the coagulability of milk as above referred tois known as the heat test. While various combinations of time andtemperature may be used in this test, I have found that the followingprocess gives satisfactory results. In order to select milk which willwithstand sterilization above the death point of paraflectum faetida, orthirty minutes at a temperature of 233 F. in the condensed state, Isubjected samples of approximately 2 cos. each of the original units offresh milk to a temperature of 278 F. for twenty minutes, placing thesamples in open test tubes of resistance lass and placing the test tubesin an autoc ave. A period of ten'minutes is allowed for advancing thetemperature of 278 F. The temperature is maintained at this point fortwenty minutes and a period of ten minutes allowed for reducin thetemperature from 278 to 212 F. I 'lk whichv is abnormal according to itsability or lack of ability to withstand sterilization, will I thistreatment, while milk which contains only normal proteins will notcoagulate.

The temperature and time of treatment in this test may be variedsomewhat to suit changing conditions, asv for instance, it it isnecessary to use a slightly higher temperature than 233 F. for thirtyminutes due 'to a greater resistance of the spore forming bacteria or toinfection by some other kind of spore former of greater resistance. Oneof the objects of my invention is to overcome the disadvantageousfeatures just set forth, and generally speaking, the invention consistsin the method by which the all) constituents of cows milk are combinedso as to produce permanent stability, and in the manner of recombiningthese constituents into the proportions of human milk. The inventionconsists of the processes finally claimed and in the products finallyclaimed, embodiments of which will hereinafter be described.

One practical embodiment of my process is carried out as follows:

A quantity of fresh milk suficient for the capacity of the factory isobtained, and to a sample from each shipping can, a heat test as abovedescribed is appliw. The milk found normal under the requirements ofthis test, is assembled, and known hereinafter as the batch. Any milkfound abnormal according to this test is rejected, and only the strictlynormalv fresh milk retained for the manufacture of this product.

A portion, approximately one half of the fresh normal milk batch, isused for the manufacture of pure lactose, and from it also is obtainedthe cream required. The lactose is recovered from this portion afterseparating the cream, and urified by re crystallization and then ma einto a supersaturated syrup. This syrup is then put through a.centrifugal clarifier or through a filter to remove any undissolvedparticles. Tt is then analyzed for per cent of lactose and retained foruse in the process. The separated cream is pasteurized, cooled, analyzedfor percentage of lactose, protein and fat, and retained for use in theprocess.

The other half of the batch of fresh normal milk is then condensed toapproximately 33% to 36% of its original volume, namel until stableemulsion between the colloi aggregate and serum takes place. lit is thenanalyzed for total ash. lit is then subjected to partial dialysis untilthe ash is reduced by from one tenth to two tenths of it's originalpercentage. It is then again analyzed for fat, lactose, protein and ash.

The proportion of lactose sweep and one required to give the relativeproportions in average human milk is then calculated. The calculated andweighted ountsof l syrup and cream are then mixed with the condensedmilk having had its ash reduced,

and the entire mixture is then homogenized. The accuracy of mixing isthen checked by a complete analysis of the mixture, and the specificgravity of the colloids and of the serum are then determinedaslhereinbeiore described. From the specific gravity of the serum and ofthe unfiltered milk, the specific gravity of the colloid aggregate (colloids and entangled fat) is calculated. In evaporated human milk, theserum is much heavier than in evaporated cows milk, on account ofthe'greater percentage of lactose. -lut,'this difi'erence 'ot thespecific gravities of the serum and colloids of human milk enables acalculation to be made asto the certain point of concentration wherestability results. Applying this calculation to the specific gravity ofthe serum and colloids as above determined, 1 am enabled to determine apoint of concentration for the milk in question where a state of balancesuspension and stability will result. Consequently, a means is providedfor making humanized milk which is stable, or of making slight changesiii the ratio of fat to rotein of it, which results in a point of staility at a desired concentration within a limited range ofconcentration. From this it follows, that in order to get stability inan artificial or modified milk, it is necessary to condense anartificial or modified milk to such a point that the specific gravity ofthe serum equals the specific gravity of the colloidal aggregate, andthe densityis determined by the composition of the milk. In order totest the accuracy of the first calculation of required density of themilk, ll subject a sample after roduct of the condensing to thecalculate point to ultra filtration as hereinbefore described and againdetermine the specific gravities ot' the serum and-of the colloid.

On account of the fact that cows milk contains considerably moreinorganic salts than human milk it is necessary to modify the inorganicsalt content, that is, the ash content otthe cows milk, in order to makeit the exact equivalent of human milk.

I have found it possible to selectively remove any desired proportion ofthe inorganic-content of cows milk by a process of partial dialysis,utilizing a membrane of certainporosity.

This process is based upon the principles of osmosis. Salts which areionized in solution are known to exert a pressure in .accordance withthe gas laws. increases as the size of the ion decreases and if thesolution of the salt is enclosed within a membrane having pores of suchsize that molecules of water and the ions can pass through themembranes, but the molecules of other substances being of This pressurelarger size cannot pass therethrough, then.

the ions of the salt will force their way through the membrane if themembrane is immersed in pure water and will thus be removed from theoriginal solution. This process is applicable to the removal of saltsfrom the milk since the salts'are ionized entirely or in part while theother constituents of the milk exist in molecules of much larger size,which are not ionized, consequently, when milk is placed in a cell madeof a semi-permeable membrane" of proper porosity and the cell isimmersed in pure water, the inorganic salts of the milk will be causedto migrate through the membrane and into the water. If this cell isimmersed for a sufiici'ent length of time all of the salts will beremoved from the milk, with the exception of those which are combinedwith proteins; By stopping the procless at therequisite point anydesired proportion of the inorganic salts may be selectively removedfrom the milk.

In a practical application of this process, afterthe removal of aportion of the inorganic salts from humanized milk I have I found thatthe desired result is obtained by using a completely gelatinized mixinga small amount of glycerine with the collodion used in preparing themembranes. I have also been able to control the porosity of themembranes by properlfy controlling the drying of the collodion be ore.immersion in water. A slight degree of drying produces. a thicker andmore porous membrane, while a greater degree of drying produces a denserand less porous '0. membrane. Any membrane having such a porosity thatlactose molecules will not readily pass, while the molecules ofinorganic salts will pass, is suitable for the process.

. In order to increase the rate of dialysis to such a point as to makethe process practicable, I have found it to be desirable to circulateboth the water and milk and instead of using sacks or cellsof theordinary type, as frequently employed .in laboratory d1al ys1s, I haveconstructed an apparatus similar in outward appearance to a filter presscarrying a large number! of memranes sliglhtly spaced from each other.Through t e. alternate cells, milk is circulated and through theremaining cells the distilled water is circulated. This circulation hasthe efl'ect of greatly increasing the rate of dialysis. I found that thearea of the membrane required to carry out partial dialysis to theapproximate-point However, in practice, four hours is found to be aconvenient length of time for the dialysis, and accordin l g a membranearea isprovided which will i amount of milk within that-length of time.

The extent to which the dialysis is carried out is determined by the ashcontent of the milk, it being necessary to reduce the ash content to acertain fixed percentage corresponding to that found in average humanmilk. The extent of dialysis 1s not necessarily the same for all lots ofcows milk handled since the percent of ash varies from season to seasonand in different 10- calities, but the extent of dialysis is readilydetermined by analysis.

Another embodiment of the process contemplates another procedure whichleads to the same result. This is to first mix the calculated weightoflactose syrup and cream with" the second portion of the batch of freshnormal milk, before condensing the milk, then condensing the mixture tothe desired point, and then partially dialyzing the same, and then homoenizing it. The emulsion is then analyze so as to verify alyze therequired the accuracy of the mixing, andthe accuracy of reaching theroper point of condensation.

The specific gravity test described is, of course, applied in carryingout this embodiment.

- By either of the embodiments described,

a condensed milk product is produced, having the relative proportions offat, protein, lactose and ash of average human milk, and of suchconcentration that the colloidal fatprotein entanglement will notseparate from the serum. And theproduct has its constitutents in stablesolution and suspension. The product has the relative proportions offat-protein and lactose of human milk, and has its inorganicconstituents or ash reduced by dialysis to approximately the proportionof average human milk.

Having secured the proper composition and other characteristics asdescribed, the product is canned and sealed in-either tin or glasscontainers and sterilized at suitable temperatures, then after beingstored for a period of several days, thecontainers are inspected forleaks, and to some of the sam les a centrifugal separation or stabihtytest is applied, after which the product is ready to be marketed. Thisstability test is applied to the finished product as ameans retrace to aseparative force equal to that which out neutralization of any of thenormal would be applied by gravity in a period of six months or oneyear, or such length of time as is selected as a maximum which it willbe necessary for the milk to keep; But in general, milk which willwithstand a test when applied equivalent to the action of gravity forsix months, is in balanced suspensionand will never separate, that is,in permanent and stable emulsion form. Thus, by this test, anyproduct'rwhich is inaccurately combined may be detected at once.

The product made according to the above process retains, uninjured, thevitamines or growth producing components. The product is not subjectedat any stage of the process to a temperature capable of injuring thevitamines that is, about 245 R, which temperature is known not to beinjurious to vitamines in acid solution. Throughout the process, thenormal acidity of fresh milk is retained. The care used in selectingnormal fresh milk makes possible sterilization withacidity of the milk.The addition of lime water or any other alkali as hereto-fore gen erallyused in preparation of humanized milk, is rendered unnecessary, sincethe milk has no increased acidit due to souring, and as it-is, in freshnorma condition will withstand steriliz'ation in the presence of itsnatural acidity. This is a very important feature, since it iswell-known that vita mines are destroyed if, held in the presence of analkali for a suflicient time, or are destroyed at once if heated in thepresence of an alkali. Furthermore, no constitutent not a normalconstituent of milk is added. Milk does not normally contain any alkali,or any compound such as formed by the neutralization of an. alkali, andthe addition of any such forei I substance as has heretofore been donein the efiort to make'the product resistant to sterilization, is harm.Tests made by suitable feeding experiments have shown that the vitaminesof this product are T have found that veryslight changes in the relativeproportion of fat to protein affects the specific gravity of thecolloidal aggregate, and consequently afiects the point of condensationat which the compound 1;.

reaches a condition of stable suspension. In case the point ofcondensation of a batch of milk where stability is reached is. found tobe too low or too high, slight additions of fat orof whole milk. may bemade:- without materially afiecting the analysis of the product, so asto give the colloidal aggregate such a specific gravity that it will be1n stable suspension at a suitable concentration. Average human milkhasthe composition, fat 3.78%, protein 2.29%, lactose 6.21% and ash 0.31%,although individual samples may var considerably from these averages. Itis t e purpose of the process herein described to make an artificialhuman milk having the components in the same relative proportions as theaverage of human milk, and of a concentration appr )Ximately twice theabove percentages, so that for use, the product will have to be diluted.On account of the fact that the 9 specific gravity of butter fat and ofprotein of milk vary appreciably from season to season, changes of a fewhundredths of a per cent in the relative proportions of fat and proteinare necessary in order to make bodiments of the process, but changes maybe made without departing from the spirit of the invention as defined inthe appended claims. The product itselfhas been described and is alsohereinafter claimed.

ll claim: 1. The procem of making a condensed modified milk whichconsists in concentrating whole milk then adding lactose and cream tobring the cows milk to the relative proportion of the constituents ofhuman milk, then dialyzing to partially reduce the ash content to therelative proportion of human milk, homogenizing t e same, and thendiluting with water to such density that the specific gravity of theserum equals that of the colloidal aggregate.

2. The process of making a condensed modified milk which consists inconcentrating whole milk, then adding lactose and cream to bring thecows milk to the relative proportion of the constituents of human milk,homogenizing thesame and then diluting with water to such density thatthe specific gravity of the serum. equals that of the colloidalaggregate.

3. The process of making a condensed modified milk which consists incondensing ml dialyzed cows milk to a point of stable suspension inwhich the colloidal aggregate and the serum of themilk are insubstantial equilibrium, homogenizing and then sterilizing the same.

4:. The process of making a modified milk which consists in. recoveringfrom one porwhich consists in recovering tion of fresh normal cows milkthe pure lactose and cream, condensing the. other portion to a'point aproximately 33% of its original volume, dia yzing the condensed portionto reduce the ash content of the condensate, adding the pure lactose andcream of the first portion to the dialyzed condensate and adduntil thecolloidal aggregate is in stable suspension in the serum,dialyzin thecondensate and homogenizmg the ialyzed condensate.

6. In the art of making modified milk the steps which consist insubjecting sample portions of cows milk to the influence of heatsuificient to coag late abnormal coagu xlable proteins, then s lectingonly that milk in which the protein does not coagulate, and

finally converting the selected milk into condensed humanized milk of acomposition equivalent to that of average human milk of equal density.

7. In the art of makin modified milk, the

step which consists in six j ecting a sample of the milk directly intoits colloidal and noncolloidal constituents to enable the specificgravity of the colloidal oonstitutents of the milk to be calculated andthen concentrating the milk until the specific gravity of the serum issubstantially equal to the specific gravity of the colloidalconstituents.

8. A condensed modified cows milk, having substantially the samerelative proportions of fat, protein, lactose and ash as average humanmilk and in which the inorganic constituents are present insubstantially the same proportion as in average human milk.

9. A modified milk product having the relative proportions of fat,protein and lactose of human milk, condensed and sterilized,and in whichthe colloidal aggregate and the serum are of substantially the samespecific gravity so as to form a stable suspension of the colloidalaggregate in the serum.

10. The process of making a condensed milk which consists in condensinmilk having substantially the same relatlve proportion of fat, proteinand lactose as human milk to a int of stable suspension in which thecolloi al a gregate and the serum of the milk are in su stantialequilibrium, homogenizingand then sterilizing the same.

In testimony that I claim the foregoing as my invention, I have si ed bname.

GEOR lli G INDROD.

